Collapsible Mandrel Tools and Associated Methods for Fabrication of Wound Composite Articles

ABSTRACT

Mandrels of various configuration, and action, including collapsible mandrels, to be used in forming composite articles with preselected three dimensional shapes and construction are disclosed and described. In one aspect, such a mandrel may have a plurality of discrete segments coupled about a longitudinal axis and collectively forming an enclosure with a substantially continuous exterior working surface. The working surface can have a network of intersecting grooves formed therein, and such grooves can cooperatively establish a substantially continuous interconnected lattice corresponding to the three dimensional geometric configuration to be imparted to a composite article formed. The mandrel may optionally include a removable core assembly to aid in collapse of the mandrel.

PRIORITY DATA

This application is a continuation application and claims the benefit ofU.S. application Ser. No. 12/542,613, filed Aug. 17, 2009 and U.S.Provisional Application Ser. No. 61/089,124, filed Aug. 15, 2008, eachof which are incorporated herein by reference in their entirety.

FIELD OF THE INVENTION

The present invention relates to collapsible mandrel devices and theiruse in methods for fabrication of wound composite articles. Accordingly,the present invention involves the fields of chemistry, materialsscience, and engineering technology.

BACKGROUND OF THE INVENTION

Mandrels have been used for years in a variety of industries forperforming many different tasks, such as lathing. Many other tasks areaided by the use of an elongated cylinder which turns about alongitudinal axis. On example of mandrel use is in shaping metal pipesor glass. Mandrels have also been used in making jewelry such as a ringsor bracelets. In addition, mandrels have been used in the formation offiber composite articles where the fibers are wound around the mandrelto create a tube and then further cured or processed into a finishedarticle.

SUMMARY OF THE INVENTION

The present invention sets forth mandrels for use in fabricatingcomposite articles having desired three dimensional configurations orshapes. In one aspect, a collapsible mandrel in accordance with thepresent invention may include a plurality of discrete segments coupledabout a longitudinal axis and collectively forming an enclosure with asubstantially continuous exterior working surface. The working surfacecan have a network of intersecting grooves formed therein whichcooperatively establish a substantially continuous interconnectedlattice corresponding to the three dimensional geometric configurationto be imparted to a composite article formed using the mandrel. Themandrel may further include a removable core assembly occupying aninterior volume of the enclosure and coupling the segments together toform the enclosure. The interior volume can have a size sufficient topermit entry of a segment into a hollow portion thereof in order toallow the mandrel to collapse and be removed from the formed compositearticle.

In addition to the mandrel devices set forth herein, the presentinvention encompasses methods of shaping a fiber-based compositematerial to be consolidated into a three dimensional structure. In oneaspect, such a method may include: 1) providing a mandrel as disclosedherein; 2) filling the grooves of the working surface of the mandrelwith a composite material; 3) consolidating the composite material inthe grooves into a three dimensional structure substantiallycorresponding to the geometric configuration cooperatively establishedby the grooves; 4) collapsing the mandrel into pieces inside of thethree dimensional consolidated structure; and 5) removing the mandrelpieces from within the consolidated structure.

Furthermore, the present invention encompasses shaped fiber-basedcomposite material assemblies. In one aspect, such an assembly mayinclude: 1) a collapsible mandrel as recited herein; and 2) afiber-based composite material preform filling the grooves of theinterconnected lattice of the working surface of the enclosure on themandrel.

There has thus been outlined, rather broadly, the more importantfeatures of the invention so that the detailed description thereof thatfollows may be better understood, and so that the present contributionto the art may be better appreciated. Other features of the presentinvention will become clearer from the following detailed description ofthe invention, taken with the accompanying drawings and claims, or maybe learned by the practice of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a longitudinal cross-sectional view of a collapsible mandrelin accordance with an embodiment of the present invention.

FIG. 2 a-h is show schematic views of various groove intersectionconfigurations in accordance with various embodiments of the presentinvention.

FIG. 3 a-h shows various geometric configurations for the cross-sectionshape of the grooves in accordance with various embodiments of thepresent invention.

FIG. 4 is a side perspective view of discrete segments to be assembledand collectively form an enclosure with a working surface for themandrel in accordance with an embodiment of the present invention.

FIG. 5 is a longitudinal perspective view of a mandrel in accordancewith an embodiment of the present invention.

FIG. 6 is a perspective view of a collapsible mandrel engaged with afinished composite article with one or more segments in a collapsedposition for removal of the mandrel from the composite article inaccordance with an embodiment of the present invention.

DETAILED DESCRIPTION

Before the present invention is disclosed and described, it is to beunderstood that this invention is not limited to the particularstructures, process steps, or materials disclosed herein, but isextended to equivalents thereof as would be recognized by thoseordinarily skilled in the relevant arts. It should also be understoodthat terminology employed herein is used for the purpose of describingparticular embodiments only and is not intended to be limiting.

It must be noted that, as used in this specification and the appendedclaims, the singular forms “a,” “an,” and “the” include plural referentsunless the context clearly dictates otherwise. Thus, for example,reference to “an abrasive precursor” includes one or more of suchprecursors, and reference to “a pressure medium” includes reference toone or more of such materials.

Definitions

In describing and claiming the present invention, the followingterminology will be used in accordance with the definitions set forthbelow.

As used herein, “fiber-based composite material” refers to a materialcomprised of carbon or other fiber (e.g., a carbon or glass fiberfilament) and resin (e.g., polymer matrix) constituents.

As used herein “preform” refers to a green, uncured composite lay-upcomprising the fiber material and resin composite as situated in grooveson a mandrel or other suitable mold, and that has undergone preliminaryshaping but is not yet in its final consolidated or cured form.

As used herein, “working surface” refers to an exterior surface of amandrel that is used to form, engage, sculpt, mold, hold, direct, guide,etc., a fiber-based composite material to be consolidated into a threedimensional article. Such working surface may have grooves or othertechnical or functional features formed therein and use of the termworking surface refers to surfaces inside the grooves or other designsor features as well as those surfaces outside.

As used herein, the term “substantially” refers to the complete ornearly complete extent or degree of an action, characteristic, property,state, structure, item, or result. For example, an object that is“substantially” enclosed would mean that the object is either completelyenclosed or nearly completely enclosed. The exact allowable degree ofdeviation from absolute completeness may in some cases depend on thespecific context. However, generally speaking the nearness of completionwill be so as to have the same overall result as if absolute and totalcompletion were obtained. The use of “substantially” is equallyapplicable when used in a negative connotation to refer to the completeor near complete lack of an action, characteristic, property, state,structure, item, or result. For example, a composition that is“substantially free of particles would either completely lack particles,or so nearly completely lack particles that the effect would be the sameas if it completely lacked particles. In other words, a composition thatis “substantially free of an ingredient or element may still actuallycontain such item as long as there is no measurable effect thereof.

As used herein, the term “about” is used to provide flexibility to anumerical range endpoint by providing that a given value may be “alittle above” or “a little below” the endpoint.

As used herein, a plurality of items, structural elements, compositionalelements, and/or materials may be presented in a common list forconvenience. However, these lists should be construed as though eachmember of the list is individually identified as a separate and uniquemember. Thus, no individual member of such list should be construed as ade facto equivalent of any other member of the same list solely based ontheir presentation in a common group without indications to thecontrary.

Concentrations, amounts, and other numerical data may be expressed orpresented herein in a range format. It is to be understood that such arange format is used merely for convenience and brevity and thus shouldbe interpreted flexibly to include not only the numerical valuesexplicitly recited as the limits of the range, but also to include allthe individual numerical values or sub-ranges encompassed within thatrange as if each numerical value and sub-range is explicitly recited. Asan illustration, a numerical range of “about 1 to about 5” should beinterpreted to include not only the explicitly recited values of about 1to about 5, but also include individual values and sub-ranges within theindicated range. Thus, included in this numerical range are individualvalues such as 2, 3, and 4 and sub-ranges such as from 1-3, from 2-4,and from 3-5, etc., as well as 1, 2, 3, 4, and 5, individually. Thissame principle applies to ranges reciting only one numerical value as aminimum or a maximum. Furthermore, such an interpretation should applyregardless of the breadth of the range or the characteristics beingdescribed.

Invention

The present invention provides mandrels for use in the fabrication offiber-based composite articles. Examples of specific composite articlesand methods for the fabrication thereof can be found in Applicants'copending U.S. Patent Applications filed Aug. 17, 2009 under AttorneyDocket Nos. 3095-002.NP, 3095-003.NP, and 3095-006.NP, each of which isincorporated herein by reference.

In some embodiments, the mandrels of the present invention may becollapsible. In other embodiments they may be solid. Referring now toFIG. 1 is shown a longitudinal cross-section view of a collapsiblemandrel 10, having a plurality of discrete segments 15, coupled about alongitudinal axis and collectively forming an enclosure with asubstantially continuous exterior working surface 20. The workingsurface has a network of intersecting grooves 25 formed therein. Thenetwork of grooves cooperatively establish a substantially continuousinterconnected lattice corresponding to a three dimensional geometricconfiguration to be imparted to a composite article formed using themandrel.

Referring again to FIG. 1 is shown a removable core assembly 30. In thisparticular embodiment, the core assembly includes a plurality of solidsupport members 35 and a central core 40. The removable core assemblyoccupies the interior volume of the enclosure formed by the assembledsegments and couples the segments together to form the enclosure.Further, the interior volume of the enclosure has a volume of sufficientsize to permit entry of a segment into a hollow portion thereof in orderto collapse the mandrel.

The enclosure formed of segments 15 as shown in FIG. 1 is asubstantially closed as the segments connect to or abut one another atthe segment junctions 65. In some configurations, as with the one shownin FIG. 1, the segments can be tightly fitted leaving no gap betweenthem, or substantially no gap. However, in other embodiments, thesegments can be loosely fitted and a gap formed at the segment junctions65.

The segments 15 used in forming the enclosure can take a variety ofshapes and sizes as required in order to form an enclosure of desireddimensions and geometry and to also create a desired working surfaceconfiguration. For example, as show in FIGS. 4 and 6, the segments canbe elongated and arcuate. As shown in FIG. 4, the segments can be a halfcircle each and two of such shaped segments may be assembled opposite ofone another in order to form a cylinder. By contrast, as shown in FIG.1, four arcuate segments can be assembled in order to form a cylindershape. In yet other aspects of the present invention, the segments maybe flat and have varying lengths. In yet other aspects, the segmentscould have other geometric configurations which lend themselves toassembly about a longitudinal axis using a removable core, such astriangular, rectangular, square, irregular, etc. Furthermore, thesegments need not be all the same shape, but can be individually shapedand matched in order to produce a specific larger overall design, suchas an airfoil, a wing, a hull, etc.

The cooperation of segments 15 is relevant to the creation of theexterior working surface 20 of the enclosure as each segment has aworking surface thereon. The working surface shape and dimensions willdictate at least in part, the configuration of the three dimensionalcomposite article produced using the mandrel of the present invention.Accordingly, in one aspect of the present invention, the exteriorworking surface of the enclosure can have a predetermined shape thatmatches a shape intended for the composite article. Such shapes can becustom configured in cooperation with the shape of the segments used inorder to provide a working surface having a cross-section perpendicularto the longitudinal axis with a specific geometric form. Examples ofsuch geometric forms may include without limitation: a circle, and oval,an ellipse, a crescent, a triangle, a square, a rectangle, a pentagon, ahexagon, an octagon, a polygon, a star, and combination or variationsthereof. In one aspect, the geometric form may be a circle. In anotheraspect, the geometric form may be a rectangle. In a further aspect, thegeometric form of the cross-section may be a square.

In one aspect of the present invention, the geometric form of thelongitudinal cross-section may extend for substantially the entirelength of the mandrel. In such cases, mandrels with regular geometriesof many different shapes may be formed, such as: a cylinder, a cone, apyramid, a triangular prism, a rectangular prism, a pentagonal prism, ahexagonal prism, a heptagonal prism, an octagonal prism, etc. Nearly anyregular and know geometric configuration can be produced. However, inone specific embodiment, the working surface shape may be a cylinder. Inanother embodiment, the shape may be an octagonal prism. In yet anotherembodiment, the shape may be a rectangular prism.

In a different aspect of the present invention, the geometric form ofthe longitudinal cross-section may extend for less than the entirelength of the mandrel. In this case, various cross-section geometriesmay be assembled with appropriate transition areas there between. Forexample, one portion of the working surface of the enclosure may begeometrically configured with a longitudinal cross-section of a square,while the longitudinal cross-section of a different portion of theworking surface may be a circle with an appropriate transition portionin between. Additionally, a single mandrel may include several sectionswith working surfaces each having different cross-sectional geometriesand transitions as required in order to produce a composite article witha specific three dimensional configuration. This may be particularlytrue when forming an article with a custom geometric shape or irregularform, such as an airfoil, a wing, a propeller, a hull, a blade, etc.

Referring now to FIG. 5, is shown a longitudinal view of a mandrel 10 inaccordance with one embodiment of the present invention. As shown inFIG. 5, the working surface 20 has a network of intersecting grooves 25formed therein. The grooves cooperatively form a substantiallycontinuous interconnected lattice that corresponds or substantiallycorresponds, to a three dimensional geometric configuration to beimparted to a composite article formed using the mandrel.

The lattice formed by the network of intersecting grooves may in someaspects employ several groove types, including longitudinally extendinggrooves (i.e. “longitudinals”), laterally extending grooves (i.e.“laterals”), or helically extending grooves (i.e. “helicals”). As ageneral matter, longitudinals are grooves running parallel to thelongitudinal axis of the mandrel, laterals are grooves runningperpendicular to the longitudinal axis of the mandrel, and helicals aregrooves running in any direction that is neither parallel norperpendicular to the longitudinal axis of the mandrel.

FIGS. 2 a-h show various possible intersection configurations for thegrooves. For example, 2 a shows an intersection of a longitudinal groove45 and lateral groove 50. FIG. 2 b shows an intersection of alongitudinal groove 45 with lateral grooves 55. FIG. 2 c shows anintersection of a lateral groove 50 with helical grooves 55, and FIG. 2d shows an intersection of longitudinal groove 45 with lateral groove 50and helical grooves 55. Other various specific cross sectionconfigurations are shown in FIGS. 2 e-2 h.

Nearly any lattice design required to produce a three dimensionalproduct of specific configuration can be formed by the network ofinterconnected grooves on the working surface of the mandrel. Inaddition, the extent of the lattice along the working surface of themandrel may also be controlled. For example, in one embodiment, theinterconnected lattice of grooves can be an unbroken, or substantiallyunbroken, lattice extending substantially around the entire enclosurecreated by the segments. In another aspect, the lattice can be a brokenlattice that extends around only a portion of the enclosure. In yetother aspects, the broken lattice can be extended around the majority ofthe enclosure, around at least half of the enclosure, around about twothirds of the enclosure, around at least three quarters of theenclosure. Furthermore, the lattice may be sectioned into specificgroups or designs around various portions of the enclosure as desired.

In addition to variations in the lattice configuration and intersectionof the grooves, the cross-section shape of the grooves may bepredetermined to correspond to a cross-section shape intended forindividual supports contained in the composite article. The variation ofsuch cross-section shapes can be used in order to impart variousmechanical and physical characteristics or properties, such as certaincompression strengths, etc. to the three dimensional composite articleproduced.

As shown in FIG. 1, the grooves 25 have a triangular cross-section shapewith a sharp vertex at the bottom of the groove. However, referring toFIGS. 3 a-h are shown various examples of possible groove cross-sectionshapes. Such examples include without limitation, a T shape with aflange at the top portion of the groove, a rectangle, a square, atriangle with a single vertex at the bottom of the groove, a halfcircle, a trapezoid with two obtuse angles at the bottom portion of thegroove, a half pentagon with two obtuse angles at the bottom portion ofthe groove, a half hexagon with two obtuse angles at the bottom portionof the groove, a half octagon with three obtuse angles at the bottomportion of the groove, as well as others. In some specific embodiments,the angles at the bottom of the grooves can have a sharp vertex orcorners. In other embodiments, the angles at the bottom of the groovescan be rounded.

In most aspects of the present invention, the top portion of the groovewill be wider than the bottom portion of the groove in order tofacilitate release of the finished article out of the grooves and offthe working surface upon collapse of the mandrel. This is especiallytrue when the mandrel is made of a rigid material as more fullyarticulated below. In some additional aspects, the cross-section shapeof the groove may be widest at a top portion of the groove and narrowestat a bottom portion of the groove. In some aspects, the width may besubstantially the same at the top and bottom portions of the groove.However, in the event that mandrel of a soft or less rigid material isused, or even in certain cases where a rigid material is used, the topof the groove may actually have a smaller width than the lower portionsof the groove, such as the middle or bottom of the groove. In suchcases, the groove can be tapered from a narrow point at the top to awider point at the bottom or middle.

Additional factors that can impact release of the article include thedegree of vertex or draft angle at the bottom of the grooves. In someaspects, the grooves may include only obtuse angles or right angles. Inanother aspect, the grooves may include a plurality of obtuse angles ator near the bottom portion of the grooves. In a further aspect, thecross-section shape of the grooves may include no acute angle smallerthan about 20 degrees. Specific examples of acute angles that can beused at the bottom of the groove include without limitation angles fromabout 15 degrees to about 90 degrees. In some aspects, such angles maybe about 45 degrees. In other aspects, the angles may be about 60degrees. In yet other aspects, the angles may be about 22 degrees.

In some aspects, the bottom of the groove may be rounded. In otheraspects, the bottom of the groove may be one or more vertex. In yetanother aspect, the bottom of the groove may be flat. In some aspects,the walls of the grooves may be vertical or substantially vertical. Insome aspects, the walls of the grooves may be angled or substantiallyangled. In yet other aspects, the walls of the grooves may contain anangle, or may be rounded

As a general matter, the dimension or size of the groove longitudinalcross-section can also be controlled along with cross-section shape, forexample, the width of the groove and the depth of the groove. In someaspects, such characteristics may be manipulated to provide the articleformed with specific characteristics, such as compression strength,lateral strength, etc. In some aspects, the grooves may have a depth offrom about 0.1 inch to about 12 inches. In another aspect, the depth maybe from about 0.1 inch to about 1 inch. In yet another aspect, the depthmay be from about 0.05 inches to about 0.5 inches. Similar ranges may beused for the width of the grooves. In one aspect, the width may be fromabout 0.1 to about 12 inches. In another aspect, the width may be fromabout 0.1 inch to about 1 inch. In a different aspect, the width may befrom about 0.5 inches to about 0.5 inches. Such sizes will be selectedbased in part on the type of article being fabricated and the scale towhich it must perform. For example, a boat hull may require grooves of asignificantly different scale than those required for a bicycle handlebar. Moreover, specific groove shape can be selected to work incombination with varied groove depth and width dimensions in order toachieve required specifications for processing and performance in thefinal article. For example, a deep groove may have a rounded bottom tofacilitate easy removal of the article.

It is of course to be understood that the grooves forming the lattice onthe working surface of the mandrel can all have substantially the samecross-section shape, or they may have different cross-sections. In oneaspect, the longitudinal grooves may have a cross section that isdifferent from the lateral grooves and the helical grooves. For example,the longitudinal grooves may have T shaped sections while the lateralgrooves and the helical grooves are a half circle. In some otheraspects, all the each groove type may have different shape anddimension, for example, the longitudinal grooves may have a rectangularshape while the lateral grooves have a triangle shape and the helicalgrooves have a circular shape. Moreover, the same types of groove canhave different shapes. For example, some longitudinal grooves may have aT shape while others have a rectangle shape. A large variety of mixingand matching of groove cross-section shape and dimension is possiblewith the present invention.

The exterior working surface of the segments of the present inventionmay be made from nearly any suitable material that can have a network ofintersecting grooves formed therein. In some aspects, such materials maybe rigid. In other aspects, such materials may be soft. Examples ofrigid materials include without limitation, metals, ceramics, curedpolymeric materials, composites, alloys, and mixtures thereof. Examplesof metals and metalloids include without limitation, stainless steel,aluminum, tungeston, titanium, iron, magnesium, nickel, chromium,manganese, boron, silicon, and mixtures and alloys thereof. Examples ofceramic or other superhard materials include without limitation,diamond, diamond-like carbon, silicon carbide, tungsten carbide, siliconnitride, aluminum oxide, boron nitride, cubic boron nitride (cBN),titanium carbide, as well as combinations thereof. Examples of curedpolymers include without limitation acrylic and acrylate polymers,silicone polymers, epoxies, urethanes and polyurethanes, and rubberbased polymers, among others, including combinations and mixturesthereof. Examples of composites include without limitation, fiber-resincomposites, carbon fiber composites, particulate-polymer composites,etc.

In some aspects of the present invention, all of the segments, orexterior working surfaces of the segments, may be made from the samematerials (i.e. all are stainless steel, etc.). However, in otheraspects, one or more segments may be made of a different material. Inaddition, when made of rigid materials, the segments may be reusable ormulti-use segments. When made of softer materials, including softermaterials or composites, the segments can be of limited time use, or ofsingle use. Such segments are thought to be disposable and in someaspects can be sacrificed or destroyed as part of the collapsingprocess.

In order to facilitate release of the formed article from the mandrelgrooves, the working surface, including the grooves, or in some aspects,only the grooves can be provided with a lubricant. Such a lubricant canbe temporarily applied prior to insertion of the fiber-based compositematerial into the grooves and/or onto the working surface (e.g. such asan oil, petroleum product, silicone lubricant, etc.), or such lubricantproperty can be more permanently affixed to the working surface (e.g.coating with a friction reducing polymer such as polytetrafluroethylene,etc.). In some aspects, the entire working surface may be coated. Inother aspects, substantially all of the grooves of the working surfacemay be coated.

Referring again to FIG. 1 is shown a cross-sectional view of theremovable core assembly 30. The core assembly occupies the interiorvolume of the enclosure formed by the segments 15, and couples thesegments together to form the enclosure. One example of a couplingmechanism that can be used is by screwing the segments to the coreassembly. Screw holes, 60 can be seen in FIGS. 4 and 5. A variety ofother mechanisms, including adhesives, clips, etc. can be used to couplethe segments to the core assembly.

As shown in FIG. 1, the core assembly 30 includes solid support members35 and solid core 40. Such support members fill substantially the entireinterior volume of the enclosure. In such an embodiment, the core or oneor more of the solid support members is pushed along the longitudinalaxis and removed from the mandrel in order to create a hollow space ofsufficient size to allow entry of one or more of the segments as part ofthe process of collapsing the mandrel. However, in other embodiments,support members may be used which do not substantially file the entireinterior volume of the enclosure and a hollow space may exist withoutremoval of the core or any core pieces.

In one aspect, the core assembly can consist of a single piece. In otheraspects, the core assembly can include multiple integrated pieces. Suchpieces can be coated with a lubricant or other friction reducingmaterial in order to facilitate their removal from the mandrel. In otheraspects, such pieces may be capable of manipulation within the enclosurein order to create or expand a hollow space and allow entry of one ormore segments as shown in FIG. 6.

As shown in FIG. 1, the core 40 has a specific configuration that keysthe placement of specific supporting members which in turn may key theplacement of the segments. Such keying can be useful in automatingassembly of the segments into an enclosure with a specific workingsurface configuration. In alternative embodiments, the core assembly canbe non-keyed and can universally couple segments to allowinterchangeability of segment location so that an operator can selectand place segments at his discretion in the creation of a custom madeworking surface.

In addition to the mandrel devices and structures disclosed herein, thepresent invention additionally encompasses methods of using suchmandrels. In one aspect, such a method includes shaping a fiber-basedcomposite material to be consolidated into a three dimensionalstructure. Such a method may include providing a mandrel as recitedherein, filling the grooves with a composite material, or a compositematerial perform, consolidating the composite material into a threedimensional structure substantially corresponding to the geometricconfiguration cooperatively established by the grooves, collapsing themandrel into pieces inside of the three dimensional consolidatedstructure, and removing the mandrel pieces from within the consolidatedstructure. One example of a mandrel collapsed inside a consolidatedstructure is shown in FIG. 6.

In some aspect, the filling of the grooves with a composite material tobe consolidated can include winding a carbon fiber or other fibrousmaterial into the grooves of the mandrel and adding a curable resin tothe fibrous material. Furthermore, the consolidation of the compositematerial can include covering the working surface of the mandrel with awrap of a flexible resilient material, such as a silicone layer, andpressing and heating the assembled mandrel and materials using asuitable pressurized heating device. Examples of such devices andmethods are more fully disclosed in the applicants' related applicationspreviously mentioned and incorporated by reference.

Furthermore, the present invention encompasses a shaped fiber-basedcomposite material assembly. Such an assembly may include a mandrel, orcollapsible mandrel as disclosed herein and a fiber-based compositematerial perform filling the groves of the interconnected lattice on theworking surface thereof. As previously mentioned, such a compositematerial perform can be applied to the mandrel by winding, filling,pasting, etc.

Of course, it is to be understood that the above-described arrangementsare only illustrative of the application of the principles of thepresent invention. Numerous modifications and alternative arrangementsmay be devised by those skilled in the art without departing from thespirit and scope of the present invention and the appended claims areintended to cover such modifications and arrangements. Thus, while thepresent invention has been described above with particularity and detailin connection with what is presently deemed to be the most practical andpreferred embodiments of the invention, it will be apparent to those ofordinary skill in the art that numerous modifications, including, butnot limited to, variations in size, materials, shape, form, function andmanner of operation, assembly and use may be made without departing fromthe principles and concepts set forth herein.

1. A mandrel comprising: a plurality of soft discrete segments formed ofa polymer and having a substantially flat configuration coupled about alongitudinal axis and collectively forming an enclosure with asubstantially continuous exterior working surface, said working surfacehaving a network of intersecting grooves formed therein, said groovescooperatively establishing a substantially continuous interconnectedlattice corresponding to a three dimensional geometric configuration tobe imparted to a composite article formed using the mandrel; and aremovable core assembly occupying an interior volume of the enclosureand coupling the segments together to form the enclosure, wherein saidplurality of soft discrete segments conform to said removable core. 2.The collapsible mandrel of claim 1, wherein the exterior working surfaceof the enclosure forms a predetermined shape that matches a shapeintended for the composite article.
 3. The collapsible mandrel of claim2, wherein the shape includes a cross-section perpendicular to thelongitudinal axis with a geometric form selected from the groupconsisting of: a circle, an oval, an ellipse, a crescent, a triangle, asquare, a rectangle, a pentagon, a hexagon, a heptagon, an octagon, apolygon, a star, and combinations thereof.
 4. (canceled)
 5. (canceled)6. (canceled)
 7. The collapsible mandrel of claim 1, wherein the shapeincludes a cross-section perpendicular to the longitudinal axis with ageometric form of a cylinder.
 8. The collapsible mandrel of claim 1,wherein the network of intersecting grooves includes intersection oflongitudinal grooves with lateral grooves.
 9. The collapsible mandrel ofclaim 1, wherein the network of intersecting grooves includesintersection of longitudinal grooves with helical grooves.
 10. Thecollapsible mandrel of claim 1, wherein the network of intersectinggrooves includes intersection of lateral grooves with helical grooves.11. The collapsible mandrel of claim 1, wherein the network ofintersecting grooves includes intersection of longitudinal, lateral, andhelical grooves at a single intersection.
 12. The collapsible mandrel ofclaim 1, wherein the grooves each have a predetermined cross-sectionshape corresponding to a cross-section shape intended for individualsupports contained in the composite article.
 13. (canceled) 14.(canceled)
 15. The collapsible mandrel of claim 12, wherein thecross-section shape is widest at a top portion of the groove and anarrowest at a bottom portion of the groove.
 16. (canceled) 17.(canceled)
 18. The collapsible mandrel of claim 15, wherein the bottomportion of the groove is rounded.
 19. The collapsible mandrel of claim15, wherein the groove shape is a member selected from the groupconsisting of: a T shape with a flange at the top portion of the groove,a rectangle, a square, a triangle with a single vertex at the bottomportion of the groove, a half circle, a trapezoid with two obtuse anglesat the bottom portion of the groove, a half pentagon with two obtuseangles at the bottom portion of the groove, a half hexagon with twoobtuse angles at the bottom portion of the groove, and a half octagonwith three obtuse angles at the bottom portion of the groove.
 20. Thecollapsible mandrel of claim 19, wherein the angles of the shapes at thebottom of the grooves are rounded rather than having a sharp vertex. 21.(canceled)
 22. The collapsible mandrel of claim 1, wherein theinterconnected lattice of grooves is a broken lattice extending aroundonly a portion of the enclosure.
 23. (canceled)
 24. (canceled) 25.(canceled)
 26. (canceled)
 27. (canceled)
 28. (canceled)
 29. (canceled)30. (canceled)
 31. The collapsible mandrel of claim 1, furthercomprising a lubricant coating coated over at least a portion of theworking surface.
 32. (canceled)
 33. The collapsible mandrel of claim 1,wherein the removable core assembly is a single piece.
 34. Thecollapsible mandrel of claim 1, wherein the removable core assemblycomprises a multiple integrated pieces.
 35. (canceled)
 36. (canceled)37. (canceled)
 38. (canceled)
 39. A method of shaping a fiber-basedcomposite material to be consolidated into a three dimensionalstructure, comprising: providing a mandrel as recited in claim 1;filling the grooves with a composite material; consolidating thecomposite perform material into a three dimensional structuresubstantially corresponding to the geometric configuration cooperativelyestablished by the grooves; and removing the mandrel from within theconsolidated structure.
 40. A shaped fiber-based composite materialassembly comprising: a mandrel as recited in claim 1; and a fiber-basedcomposite material filling the grooves of the interconnected lattice.